ToME: the Tales of Maj'Eyal

When siding with the Grand Corruptor you become friendly with his faction (Rhalor, sp).

Afterwards, the crypt becomes very easy since almost all of the mobs there are friendly to you. They are probably supposed to become unfriendly if you start killing them.

Yes, in next beta hitting friendlies will kinda aggravate them, and their friends in LOS

Wasn't that the case already? I clearly remember Aeryn hit by a buggy Chain Lightning spell turning hostile...

Not the same thing, a few specific factions would turn hostile when attacked, but the whole faction.
This is on a creature per creature basis

Side note: the crypt was moderately entertaining as-is, at least one time I was there, as the "monster" monsters and the "Rhalore" monsters apparently didn't get along, even though both of them had 100% hate for me. Don't know if this is a bug or not.